Devices have been proposed for synchronizing the speeds of two or more engines, each of which is controlled by a hand throttle lever acting through an associated cable, linkage or other similar means on a throttle lever of the engine. Typically, these prior devices adjust the speed of one engine (commonly referred to as the "slave engine") by moving the throttle lever associated therewith until the speed of the slave engine substantially matches the speed of the other engine (commonly referred to as the "master engine").
Generally, the prior synchronizing devices adjust the speed of the slave engine by moving the throttle lever associated with the slave engine. In addition to moving the throttle lever of the slave engine, many of these devices also move the hand throttle lever associated with the slave engine (see, for instance, U.S. Pat. Nos. 3,258,927 and 2,339,989). These devices are disadvantageous because they must generate sufficient force to overcome not only the friction of the throttle lever but also the friction of the hand throttle lever and the cable or linkage connecting the hand throttle lever to the throttle lever.
In other of the prior synchronizing devices, apparent attempts have been made to synchronize the speed of the slave engine with the speed of the master engine without having to move the hand throttle lever associated with the slave engine. Some of these devices require the modification of the cable which connects the hand throttle lever of the slave engine to the throttle lever on the slave engine (see, for instance, U.S. Pat. Nos. 3,367,110 and 3,309,871). In particular, these synchronizing devices are interposed intermediate the ends of the linkage cable connecting the hand throttle lever to the throttle lever, thereby requiring additional mounting hardware and space. In Beaman, et al. U.S. Pat. No. 3,986,363, there is disclosed an engine synchronizer which may be installed without replacing or modifying a conventional Bowden cable or similar throttle control cable used to couple the throttle lever of the slave engine to its associated hand throttle lever. However, the device disclosed in the Beaman et al. patent adjusts the position of the throttle lever of the slave engine by moving the control cable associated therewith. One problem associated with such a device is that it requires a certain amount of free space to accommodate movement of the control cable. Another disadvantage is that the stiffness of the control cable may result in erratic movement of the synchronizer.